This invention is concerned with a device for producing photographic prints from transparencies such as slides, preferably employing an instant film pack as the printing medium.
In the past, a number of devices have been described for producing photographic productions or prints from black and white negatives and slides. For example, in my prior Swiss Pat. No. 598,614, patented Nov. 15, 1978, a slide printer is provided comprising a housing having a front panel and a rectangular opening at the raised section forward of the panel. A ground glass covers the opening and thereover is fitted an instant film pack. A dark compartment is located in the housing beneath the glass containing an angled mirror and a lens. Knobs external to the housing for adjusting lens aperture and telescoping are linked to the lens. Another compartment is located beneath the panel which houses a light source at one side bounded by two reflecting mirrors. A third mirror is located to the side of the light source and is angled to reflect light toward the lens. Between the angled mirror and the lens is, in order, a diffuser, a filter and a slide, each removably retained in holders.
One disadvantage of the device of my prior Swiss patent was that the light source used therein comprised a quartz light which did not match the Kelvin rating of the instant film contained in the film pack. Such films, as currently manufactured have a daylight Kelvin rating of about 5400 Kelvin. Quartz lights, have a Kelvin rating of about 3400 Kelvins so it is necessary to use filters in such device to increase the Kelvin rating to match the rating of the film. Moreover, quartz lights develop significant amounts of heat, need to be exposed for longer periods of time to produce a satisfactory print and often cause buckling of the transparency.
In U.S. Pat. No. 3,065,667 to H. E. Edgerton an apparatus for making enlarged prints from transparencies or slides is described. The apparatus comprises a light-tight housing having at the top a processing head which can be a self-developing "Polaroid" camera with its film portion facing inwardly of the housing. The slide is placed in a holder beneath which is a light source such as a flash unit. A lens whose aperture may be controlled by a diaphragm is located between the slide and film and focuses an enlarged image on the film. Other printing devices have been described in the art which employ a camera as the medium for production of the photographic image. Such devices have been described in U.S. Pat. Nos. 4,076,413; 3,689,148; 3,454,943; 3,697,175 and 3,653,760.
The present invention is an improvement over my prior Swiss patent and is characterized by a more efficient and simpler design, that is, it does not contain a plurality of light reflecting mirrors or lens telescoping means. Moreover, the present invention employs the use of a flash unit having a Kelvin rating which matches the daylight rating of the instant film. In order to break up the contrast of the print an opalescent glass or opalescent plexiglass plate is employed between the flash unit and the instant film pack. Without such plate the contrast of the print would be too high. The plate acts to produce a soft print on the instant film.